Conventional titanium alloys are highly reactive, particularly when molten. The extreme reactivity of molten titanium alloys has required that the melting and casting of such alloys be carried out using skull techniques. In melting titanium using a skull technique a water cooled copper container is provided and the melting of the titanium alloY takes place under conditions which provide for solidification of an initial layer of the titanium composition on the water cooled copper chill surfaces so that the molten titanium alloy contacts only solid titanium rather than the copper container itself. Such techniques are necessary because of the reactivity of titanium but are also desirable because the molten product is free from contamination. Skull melting techniques have drawbacks including the limitation on the amount of superheat which is a consequence of the necessity of maintaining a solid skull between the molten material and the copper shell plate. In practice this leads to the requirement that the superheat in the molten titanium be not greater than about 40.degree. F. This limitation on superheat in turn can lead to casting problems relating to a lack of fluidity in the molten titanium with such a low superheat. The limitation to low superheat means that complex titanium castings are very difficult to produce so that most complex titanium shapes are produced by forging, an expensive process.
The reactivity between pure titanium and commercial titanium alloys and carbon is extremely high as a consequence of the high energy of formation of titanium carbides. In practice this high reactivity and the detrimental effect of carbon contamination on the mechanical properties of the resultant alloys have required that carbon be excluded from contact with molten titanium.
Recently a new class of Beta titanium alloys has been developed. These alloys are described in U.S. patent applications Ser. No. 948,390 filed Dec. 23, 1986 and U.S. Ser. No. 004,206 filed Dec. 23, 1986 which are continuations-in-part of Ser. No. 815,606, filed Jan. 2, 1986, now abandoned and are comprised of major constituents titanium, vanadium and chromium with an example alloy being Ti-35% vanadium - 15% chromium. Despite being formed from alloy constituents which all are energetic carbide formers it is a surprising observation that alloys of the approximate composition described above are relatively nonreactive with carbon.